Hi Lawrence, Oh dear, how much more evidence do you want? I'm busy now with other matters so I haven't read your message thoroughly -- but here's a quick note for now.
How was it that the most experienced firemen in the world drove right up to the Towers with their fire tenders -- which thus tragically cost them over 300 lives -- unless they were expecting that these buildings would continue to stand up in the same way that every other building in the world has hitherto, however badly they were on fire? In my childhood, after the German blitz on Coventry, I saw many buildings that were completely burned out by incendiary bombs -- but they were all still standing afterwards. No building should ever be built unless there's a 100% certainty that it would remain standing while firemen had a chance of tackling a fire. Since my previous messages, I've been discussing this with a (Canadian) friend who tells me that he understands that brand-new, hitherto untested, welding techniques were used in the construction of these buildings. And, yes, he confirms my strong suspicion in that it is his understanding that the floors were welded to the (thin) cladding -- and not riveted as they should have been. If the latter, the floors would then have withstood any sudden collapse of the floor above them. The worst that might have happened is that one (or perhaps) two floors would have subsided (relatively gently) onto the floor below with no successive compressive collapses downwards. As to my suggestion of a firemens' pole type of emergency exit -- well, imagine that the buildings had about 50/100 firemens' poles running right down through them. The poles would be nicked every 12-20 feet or so. Imagine at the side of every pole on every floor there'd be spring-loaded, ratcheted 'life-wraps' available on each floor to which individuals would strap themselves and then clip onto the poles. Evacuees would then drop down at pretty high, but constant, speed, all the way down in a matter of minutes. Such firemen's poles and the storage of 'life-wraps' (which would not need to be larger than, say the lifejackets on airplanes) would not cost the earth, nor occupy much volume on each floor. In my previous messages, I was worried that the blind anger that has been (understandably) aroused by the terrorist attack should not obscure the fact that the buildings were flimsy. However, on reflection, I think we can confidently expect that the New York Fire Department will call for a full enquiry. No New York fireman will ever tackle a burning skyscraper again built with similar methods. If there are other similar buildings in the same Trade Center complex (and I believe there are) then I think we can be sure that they'll be pulled down pretty soon -- and not because they are necessarily expecting further airplane crashes, but because fires are always a possibility. (Incidentally, I'd be pretty sure that the Empire State Building would withstand the crash of one of these modern Boeings. Forget the fuel payload and the intensity of the fire -- this is not crucial as I've already discussed. Remember that (passenger) airplanes are relatively light affairs for their size and would not have had totally destructive impact on the Trade Center buildings had the latter been constructed with riveted steel frames (or with the floors properly set into concrete columns). Keith At 10:17 30/09/01 -0400, you wrote: > > >Hi, Keith, > >> At 15:09 29/09/01 -0400, you wrote: >> >Steel melts at between 1200 and 1600 degrees. The fire caused by >> the planes >> >with their full fuel loads is calculated to have reached 2000 >> degrees. The >> >structural steel melted. Nothing shoddy about the design or construction. >> > >> >Lawrence >> >> Yes, I'm well aware of this. But the Towers did not collapse due to fire. >> That would have accounted for the yielding of only one floor of the >> buildings. The progressive collapse of the rest was due to inherent >> structural weakness. > >But Keith, EVERY structure has weakness (even the Sphinx). The question is >whether a building is built properly for the anticipated range of events >that can happen to it. The Empire State Building crash has virtually no >similarity from an engineering point of view: as you say, it was a much >smaller plane, with little fuel aboard. This makes all the difference. I can >imagine that concrete walls would do better than glass windows, certainly, >but to say that the Empire State Building would have survived Sept 11 is, at >the very best, a guess. > >Somebody also referred earlier to asbestos. As I understand this, asbestos >was only used to the 40th floor of Tower One. Is this good or bad. The >person who referred to the asbestos was exercised about the spread of >asbestos dust. Good point (especially for smokers), but then one could also >argue that if asbestos (still one of the best fire protectors) had been used >throughout, that the steel beams would have been protected that much longer >and that firemen might have reached the burning areas in time to cut the >heat down and preserve the building. Engineering, especially in situations >of failure, is a complicated thing, and the postings about the Towers have >been pretty thin -- more in the nature of rumors and accusations than true >engineering thought and analysis. > >The main point I would like to share is that engineering solutions depend on >assumptions about the stresses that will be placed on the structure. Unless >someone can argue that the crashing of a fully fueled big jet into the >buildings was reasonably foreseeable, they have little justification in >saying that the building design was inadequate. Of course it turned out to >be what happened, and with the advantage of hindsight one can make oneself >out to be a genius. How come anti-airplane missiles were not mounted on the >Pentagon rooftop? How come the Towers were not encased in 2 feet of >concrete? How come you don't brick up your windows? How come you don't >drive a humvee? How come you don't use a taste-tester? How come you ever get >into an airplane? How come you use a microwave? A cell phone? How come you >go to the movies? Swim in public pools? How come, how come, how come? Well, >we make our best predictions about the likelihood of things happening (and >many things we don't even think of at all) and then we do our best. >Engineering, like just about everything, is like that, too. > >Rumsfeld on NBC this morning said that no one in the Pentagon ever conceived >that a commercial jet liner would ever be used to crash into the Pentagon. >Does that mean the Pentagon was poorly engineered? No, it means that human >imagination on examining the bad things that > >There are several reasons that a person might say so (e.g. professional >jealousy, the natural tendency to want to blame others when something >frightening occurs, a desire for attention or seeming superiority, etc), but >that does not mean the assertions are at all credible. In this time of hurt >and anger, it is doubly important that we not contribute to the noise that >unreasoned blame inserts into the situation. > > >> >> The Empire State Building also sustained the full impact of an airplane >> fifty-odd years ago. It was a smaller plane with a smaller fuel tank, but >> the building was properly designed and constructed. The impact >> devasted one >> floor only. > > >> >> And another thing while I am at it. In very tall buildings >> where it takes >> >> occupants well over an hour to walk down the stairs in emergencies (as >> >> occurred in the Towers), there needs to be another mode of exit. An >> >> inertial variant of fireman's pole (on a ratchet or absailing >> principle) >> >> could easily be designed for escape within a few minutes on any floor >> >> (*and* without people trampling over one another, *and* which blind and >> >> handicapped people could also safely use). > >Interesting idea.... Can one design such a system that would not require >training of the possible users? > >My guess is that for emotional if no other reasons, new replacement >buildings will be a lot shorter. > >Lawrence > > > > ___________________________________________________________________ Keith Hudson, General Editor, Calus <http://www.calus.org> 6 Upper Camden Place, Bath BA1 5HX, England Tel: +44 1225 312622; Fax: +44 1225 447727; mailto:[EMAIL PROTECTED] ________________________________________________________________________
